1. Field of the Invention
The present invention relates to a run-flat tire that is capable of achieving weight saving without harming running performance in the presence of a puncture (hereinafter referred to as “run-flat performance”).
2. Description of the Prior Art
Various kinds of run-flat tires have been suggested. These run-flat tires are possible to perform continuous running in a stable manner for a specified distance at relatively high speed even when a tire has become flat due to puncture or similar. In such types of run-flat tires, sidewall reinforcing rubber layers having substantially crescent sections are disposed at sidewall portions. In case of a tire puncture, the sidewall reinforcing rubber layers support much of the load of the tire.
In order to increase the distance of running after a puncture (hereinafter also referred to as “run-flat running”), the thickness of the sidewall reinforcing rubber layers is made to be quite large. However, such sidewall reinforcing rubber layers remarkably increase the tire weight. Accordingly, so-called unspring weight of the vehicle becomes large, which worsens the steering stability and fuel consumption performance.